Jolie (l) called Eastwood an "amazing" director to work for
Angelina Jolie has said her role as a single mother whose son goes missing in Clint Eastwood's film Changeling let her "spend time" with her late mother.
Critics have praised the 1920s period drama, which is based on a true story.
Jolie and Eastwood are at the Cannes Film Festival, where Changeling is up for the prestigious Palme d'Or.
The actress, who is pregnant with twins, said it "was a way to kind of revisit my mother after (her) passing".
Jolie's mother, who died last year, was "very sweet," she added. "But when it came to her children she was a lion."
Variety called the film "emotionally powerful and stylistically sure-handed," while Screen Daily said it boasted a "career-best" performance from its leading lady.
In the film Jolie plays a single mother whose son goes missing
Jolie, 32, said she could not "imagine anything worse" than losing a child and had tapped into her own "pain and frustration" in playing the role.
"Children in danger is about the highest form of drama you can have," agreed Eastwood.
The veteran director, who turns 78 next week, was last in Cannes with 2003's Mystic River, another film about a missing child.
Not winning the Palme d'Or on that occasion, however, did not deter him from competing for the award again.
"To play it out of competition is kind of playing it safe," he said. "I'm not above it - I put it out there for what it is."
Asked why he had not cast himself in the film, Eastwood said there was no suitable role for him.
"I'm gradually working my way round to spending more time behind the camera than in front," he added.
The actor and director will introduce a special screening of his 1971 film Dirty Harry at the festival but denied he was considering reprising the central role.
"That rumour's incorrect," he joked. "Dirty Harry would not be in a police department at my age."
Reviews editor of trade paper Screen Daily, Fionnuala Halligan, said she did not believe Eastwood would be taking home a prize from Cannes this year. "It didn't feel like a Palme D'Or film to me, its more an Academy Award-type of film," she told the BBC.